Author Question: The Upper Mississippi River and the Lower Mississippi River have very different stream morphologies ... (Read 158 times)

kodithompson · **on:** Jul 15, 2018

The Upper Mississippi River and the Lower Mississippi River have very different stream morphologies due in part because of the geology of the two regions.

What is the basic geology of each region (What material is the river flowing over?), how does the geology control the river, and what is the morphology of the river as a result?What will be an ideal response?

Question 2

What are the four factors that affect stream velocity and how will they affect the flow?

What will be an ideal response?

peter · **Reply #1 on:** Jul 15, 2018

Answer to Question 1

Answer: The Upper Mississippi River is a bedrock-dominated system, which generally contains the river in one location and doesn't allow major lateral migrations. As a result, the morphology of the river is closer to a straight channel. The Lower Mississippi, on the other hand, is an alluvial stream and flows over deltaic sediments deposited over the last few million years. These sediments cannot lock the Mississippi in one location, so the river has historically migrated, cutting broad meander loops and creating oxbow lakes. The channel morphology of the Lower Mississippi is a meandering stream.

Answer to Question 2

Answer:
1) Gradient = slope of a stream channel. The steeper the gradient, the more gravitational energy there is to drive flow
2) Channel shape = the cross-sectional shape of the channel, which determines the amount of flow in contact with the banks and bed of the channel. The most efficient channel is the one with the smallest wetted perimeter, so the smallest frictional drag on the water.
3) Channel Size and Roughness = how the water flow will be affected by frictional resistance of the channel. The more frictional, the slower the flow.
4) Discharge = the volume of water passing a point in a given time. When discharge increases, flow velocity increases.